In general, compared to a natural marble, artificial marbles made of acrylic resin have various advantages, such as a fine external appearance, a high processability, a lightweight, and a high strength, thus being widely used as materials for counter tables and other interior products. However, the artificial marbles have a limit to express a similar pattern to that of the natural marble or granite from the general combination of single-colored opaque chips.
The artificial marbles made of acrylic resin are manufactured by mixing a filler, such as aluminum hydroxide, calcium carbonate, or a silica, other pigments, and a hardening agent to a syrup mixture, which is obtained by mixing a monomer, such as methylmethacrylate, with polymethyl methacrylate, casting the mixture using forming die or a continuous steel belt, and hardening the obtained product.
In order to form a pattern and a color of the artificial marble, pigments and chips are used. The chips are generally made of the same resin as that of the artificial marble, and pigments and fillers are put into the resin composite so that the chips have the same specific gravity as a raw material composite for the artificial marble, to which the chips are applied. Then, the chips are manufactured through the same process as the artificial marble, and are crushed so that the crushed chips have various colors and particle sizes.
Specifically, when an artificial marble containing the above chips is manufactured, the occurrence of layer separation due to a difference of specific gravities between the artificial marble and the chips needs to be minimized. Thus, after the specific gravity of the chips is adjusted using an inorganic filler, such as coal or aluminum hydroxide, so that the specific gravity of the chips is equal to that of a base material of the artificial marble, various pigments are put into the resin composite for the chips. Then, the resin composite is formed in a plate shape, and is crushed into the chips. When the chips are made of acrylic resin, the chips become opaque due to the filler added to the raw material of the chips, thus being incapable of imitating quartz of natural granite or marble.
Further, when transparent chips manufactured using a transparent polymer made of a single component without the addition of a filler are applied to an artificial marble, the size and the supply amount of the chips contained in the marble are limited due to chip separation caused by a difference of specific gravities between the chips and the raw material composite for the artificial marble. Accordingly, the above transparent chips cannot imitate quartz contained in the natural marble.
Korean Patent Registration No. 491874 discloses an artificial marble containing (A) an artificial marble slurry at an amount of 100 parts by weight containing acrylic resin syrup at an amount of 100 parts by weight, an inorganic filler at an amount of 120˜200 parts by weight, a crosslink agent at an amount of 2˜10 parts by weight, and a polymerization initiator at an amount of 0.1˜10 parts by weight, and (B) marble chips at an amount of 5˜70 parts by weight containing acrylic resin syrup at an amount of 100 parts by weight, an inorganic filler at an amount of 100˜150 parts by weight, a crosslink agent at an amount of 2˜10 parts by weight, and a polymerization initiator at an amount of 0.1˜10 parts by weight, wherein the mixture rate of the inorganic filler in the artificial marble slurry is higher than that in the marble chips by 20˜50 parts by weight. The marble chips obtained by adding the inorganic filler to the acrylic resin, disclosed in the above Patent, are opaque, thus being incapable of imitating quartz in a natural marble or granite.
Accordingly, in order to overcome the above technical limitation of the conventional artificial marble, the present inventor(s) has invented an artificial marble containing transparent chips, obtained by coating transparent polymeric resin, such as acrylic resin or PET with a high specific gravity resin layer containing a filler using co-extrusion and cutting the obtained extrudate, so that the transparent chips have a specific gravity similar to that of a raw material composite for the artificial marble, thereby allowing the transparent chips to exhibit transparency like quartz or high-purity silica contained in a natural marble, and thus expressing a pattern more similar to that of the natural marble, compared to a conventional artificial marble containing chips made of opaque or semi-transparent single component.